1. Field of the Invention
The present invention relates generally to the field of tools used in the oil and gas industry, and more particularly, to a tool that is designed to create an impression of an object in an oil well hole.
2. Description of the Related Art
In the oilfield, occasionally tools, wirelines and pipes will break off when down in the well hole. When this happens, a “fishing” company is called in to retrieve the broken object. In order to retrieve the object, the operator needs to know the shape of the object so that he can ascertain the best way to secure and remove it. Currently, the standard tool used to determine the shape of an object located downhole is called an “impression block.” An impression block is essentially an attachment that holds a slab of soft lead. The impression block is sent down the well hole, rammed into the stuck object, and then pulled out of the well hole for inspection. The operator then inspects the impressions left in the slab of lead to glean what information he can about the shape of the object with which it came into contact.
This method has a number of disadvantages. The markings in the lead slab are typically only about half an inch deep, which provides limited information about the overall shape of the object in the well hole. Inaccurate or incomplete information about the shape of the object can cause the operator to use the wrong grabbing tool, which in turn leads to longer retrieval times and higher costs. With the present invention, the inventors have created a tool that captures a significantly greater degree of information about the shape of the downhole object, thereby eliminating extra time and cost from the process. The automatic brake system of the present invention is key to its functionality in that it locks the elongated rods into place once the image has been taken. Other inventions for determining the shape and/or ascertaining the position of objects in oil wells are described below.
U.S. Pat. No. 2,824,378 (Stokes, 1953) discloses an apparatus for determining the contour and position of obstructions in wells. The device comprises a tubular body with an open lower end and a plurality of elongated elements mounted within the body for longitudinal movement relative thereto. The lower ends of the elongated elements are positioned for engagement with an object in the well bore so that the elements move longitudinally in accordance with the contour and position of the object. When the lower ends of the elongated elements encounter an object in the well hole, the elements move longitudinally upward within the body of the device. Longitudinal movement of the elongated elements is restricted by friction material situated within the body of the device. To reset the device, a plunger pushes down on the upper ends of the elongated elements.
U.S. Pat. No. 8,307,895 (Lund, 2012) provides a method and apparatus for imaging objects in a wellbore using a plurality of actuatable members that are axially displaced to form an image of the object. An actuable member displacement sensor detects the displacement of the actuatable members. The actuatable members are coupled to some form of drive mechanism (spring, gravity, magnetic, hydraulic, etc.) that extends and/or retracts the actuatable members. The axial displacement sensor is positioned on any portion of the imaging apparatus.
U.S. Pat. No. 8,403,056 (Gene et al., 2013) discloses a system and method for verifying support hanger orientation within a wellhead housing. This invention utilizes the conventional “impression block” described above in the Background section. The invention is a running tool with an annular mandrel and a connector at the upper end of the mandrel to connect it to a drill pipe. The running tool includes a cylindrical body with a lead block assembly mounted within it. The purpose of the lead block assembly is to generate an impression of the casing hanger within the wellhead housing.
U.S. Pat. No. 8,727,755 (Guidry et al., 2014) provides a system and method for obtaining an impression of an object in a remote environment (as in a well hole). An impression block is affixed to a running string and used to form an impression of an object. The impression block comprises a retaining section and an impression section. The impression section is formed of a shape memory material that changes shape at or above a predetermined transition temperature and a metallic shape memory alloy that changes shape below a predetermined transition temperature.
U.S. Patent Application Pub. No. 2014/0138969 (Guidry et al.) describes a fishing guide for directing a skewed fish in a wellbore. The guide has an open end and a finger structure comprised of a shape memory alloy. The fingers are retracted as the tool passes through a restriction. Once past the restriction, heaters on the fingers cause the alloy to heat up to its transition temperature, thereby causing the lower end of the guide to fan out and surround a skewed fish that is in a slanted position and leaning on a wall of a surrounding tubular that has a larger dimension than the restriction. The assembly is advanced until the fish is captured by the tool and pulled out of the hole, and the fingers are forcibly retracted as the assembly is pulled back through the restriction.